Web tensioning device



Nov. 16, 1943. "H. ALOTZI wsa mnslonme DEVICE FiledJ uly 24, 1939 4 Sheets-Sheet I H IN; M w Q mi Patented Nov. 16, 1943 WEB TENSIONING DEVICE Herbert A. Lotz, Minneapolis, Minn., assignor to Wood Newspaper Machinery Corporation, Plainfield, N. J a corporation of Virginia Application July 24, 1939, Serial No. 286,102

Claims.

My present invention relates to the control of a roll of web material and the tensioning of its web between said roll and a printing press or other machine into which the web is fed. This invention, while intended for general use, is especially well adapted for use in connection with a modern rotary printing press where the high efiiciency thereof can only be obtained, in the production of a high quality product, by the proper tensioning of the paper web from the time it leaves the live roll of paper until it is drawn into the printing press, and with the least possible chance of interruption, due to mechanical failure, a badly wound roll of paper, and the like.

It is well known that the braking effort required to control a roll of paper progressively decreases in proportion to the diameter of the roll as the same is progressively decreased by the unwinding of the web from said roll.

It is also well known that the web tension, during normal running speed of a printing press, and during acceleration or deceleration of the speed thereof, should remain constant, and that to control that uniformity of web tension, a variable and automatic, as well as manual means could be applied, and in case of sudden stopping of the printing press, to prevent the roll from running ahead under momentum and thereby put slack in the web, more braking effort is required.

It is an object of this invention to provide a friction braking member having a circumferential wrap with the periphery of a roll of paper, and for holding said member with a minimum braking effort on the roll when the printing press is stopped, for progressively and automatically increasing this braking effort during acceleration of the printing press, for holding said member with a constant and predetermined braking eii'ort on the roll during normal running of the printing press, and for progressively and automatically decreasing the braking effort during deceleration of the printing press.

A further object of the invention is to progressively decrease the circumferential wrap oi the braking member on the roll in proportion to the progressively decreasing diameter of the unwinding roll, as in relation to the full roll.

A still further object of the invention is to automatically increase the braking effort of the friction member on the roll above that applied during normal running of the printing press in case tension on the web is suddenly reduced.

Other objects of the invention will be apparent from the following description, reference being had to the accompanying drawings.

To the above end, generally stated, the invention consists of the novel devices and combinations of devices hereinafter described and defined in the claims.

In the accompanying drawings, which illustrate I the invention, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a view partly in end elevation and partly in section taken substantially on the line i-l of Fig. 2;

Fig. 2 is a fragmentary rear elevation with the basement and sub-basement floors sectioned substantially on the irregular line 2-2 of Fig. 1;

Fig. 3 is a view principally in plan with some parts sectioned on the line 3-3 of Fi 1;

Fig. 4 is a detail view partly in side elevation and partly in section taken on the line 4-4 of Fig. 3, on an enlarged scale;

Fig. 5 is a detail view partly in end elevation and partly in section taken on the line 5-5 of Fig. 4;

Fig. 6 is a left-hand end elevation of certain parts shown in Fig. 4;

Fig. '7 is a fragmentary detail view partly in plan and partly in section taken on the line l-l of Fig. 4;

Fig. 8 is a detail view principally in section taken centrally and vertically through the combined reducing and relief valve shown in Fig. 1, above the upper floor;

Fig. 9 is a detail view principally in section taken centrally and vertically through the reducing valve shown in Fig. 1 between the two floors;

Fig. 10 is a fragmentary detail view showing one of the tension units as the same appears in Fig. 3, with the exception that the cable and weight are shown by means of full lines instead of broken lines, as shown in Figs. 1 to 4, inclusive;

Fig. 11 is a fragmentary detail view in rear elevation of the tension unit shown in Fig. 10; and

Fig. 12 is a fragmentary view corresponding in part to Fig. 1, but showing a modification of the roll-engaging friction member.

The numerals l4 and i5, indicate what may be assumed to be the basement and sub-basement floors, respectively, of printing press-rooms in a newspaper building, and the numeral I6 indicates a pit in the sub-basement floor l5.

As this invention relates only to the control of a roll of material, in the form of a web, as the same is being rotated by the unwinding of its web therefrom and the tensioning of its web from the time it leaves the live roll until it is drawn into the machine, it is not thought necessary to illustrate said machine, or any part thereof, except certain of its directional rolls over which the web travels from the live roll to the machine, as will hereinafter appear. Hereinafter, the machine will be referred to as a "printing press, and the roll of material as a roll of paper.

The numeral ll indicates a reel of a wellknown commercial type and having a capacity for holding three rolls of paper, either full length,

three-quarters length or one-half length. This reel H has three sets of radial arms and each set thereof is provided with means for rotatably supporting a roll of paper thereon. The rolls of paper on the reel l1 are designated by the letters or, y and z, the roll 1 is the active or live roll, and its web w is being unwound therefrom by the operation of the printing press into which it is being drawn; and the rollers :r and z are new rolls, the roll .2 being the next roll to be brought into position as the roll 1/ expires.

The reel l1 further includes a shaft i8, about the axis of which said reel is rotated. This shaft I8 is joumaled in end bearings |9 anchored to the floor H at the ends of the pit It. To successlvely bring the rolls of paper on the reel |1 into active position, said reel is manually controlled and intermittently rotated by a pinion 20 driven by an electric motor, not shown, and which pinion meshes with a gear 2| keyed to the shaft l8 at one end thereof.

To bring the new roll 2 into active position, the reel |1 is'rotated-in the direction of. the.ar row marked" on Fig. l of the drawings, between therolls' 1r and z, and at which time a so-called flying meter is made'to'connect the two webs,

of the rolls y and 2.

" From the roll of paper 3;, its web w passes over a directional roll 22, around a yieldingly held roll 23, under and around a directional roll 24, and from thence, said web passes through an opening in the floor I4 and over a directional roll 25 to the printing press. The directional rolls 22 and 24 are journaled in fixed bearings in brackets 26, only one of which is shown, secured to and depending from the under side of the floor H. The yieldingly held roll 23 is journaled in bearings 21 slldably mounted in the brackets 26 and coiled springs 28, compressed between the brackets 26 and sliding bearings 21 yieldingly press the roll 23 away from the rolls 22 and 24. By reference to Fig. 1, it will be noted that the directional roll 24 is vertically spaced directly above the roll 22 and that the roll 23 is midway between the rolls 22 and 24 and spaced horizontally forwardly therefrom. The web w is unwound from the roll 11 at the back thereof and the directional roll 22 holds said web, as it leaves roll y, in an upwardly and forwardly inclined position.

The roll 23 holds the web w looped between the rolls 22 and 24 and the springs 28, as heretofore stated, are under strain to move the roll 23 away from the rolls 22 and 24 and thereby lengthen the loop in the web w and take up any slack in said web.

Or in other words the path of the center of roll 23 moves in a line perpendicular to a line drawn between the centers of rolls 22 and 24.

The parts thus far described, except for the spring pressed roll 23, are of standard and well known construction.

Referring now in detail to the invention, which, as shown, includes four separate and distinct tension units. Each tension unit, as shown, includes an endless friction belt 29 that runs over upper,

lower and intermediate directional devices which,

as shown, are flanged pulleys 30, 3| and 32, respectively. The upper pulley 36 is fixed to a shaft 33 journaled in bearings 34, only one of which is shown, secured to and depending from the under side of the floor i4. Said shaft 33 has a gear 35 fixed to one. end thereof and driven by an electric motor or any other suitable means, not shown. It will be noted that the driven pulley 30 is materially above the active roll y and slightly rearwardly of a vertical line that passes through the axis about which said roll turns on the reel H.

The lower pulley 3| is loosely journaled on a short shaft 36, the end portions of which are mounted in the side members of a yoke-like crosshead 31. This cross-head 31 is slidably mounted in a cross-head guide 38 in the form of a cylinder having upper and lower slots 39 which extend substantially the full length of said guide. The outer faces of the side members of the crosshead 31 have the same transverse curvature as the internal walls of the cross-head guide 38. Said cross-head guide 38 holds the cross-head 31 for straight-line travel, and the pulley 3|, which extends through both slots 39, prevents said crosshead from turning about its axis relative to the cross-head guide 38, and at the same time the pulley 3| is free to rotate about the axis of the shaft 36 and move bodily with the cross-head 31 during its endwise travel in the cross-head guide 38.

The cross-head guide 31 has on its sides a pair of angle-bar legs 4|] which are anchored to the inclined rear wall of the pit l6, These legs 40 support the cross-head guide 38 in an upwardly and rearwardly inclined position, with its rear end portion in the pit l6, and with its axis aligned with a radial line extending from the axis of the pulley 32.

Mounted on the rear or upper end of the crosshead guide 38, in axial alignment therewith, is a cylinder 4| in which a co-operating piston 42 works. This piston 42 is connected by a rod 43 to the cross-head 31. A yoke 44 is secured to the rear ends of the side members of the cross-head 31 and extends transversely of and below the pulley 3|, for a purpose that will presently appear.

The pulley 32 is fixed to an idle shaft 45 journaled in adjustable bearings on brackets 46 anchored to the floor l5 rearwardly of the pit I6. It is important to note the peculiar relation of the pulleys 30, 3| and 32 to each other and t0 the live roll of paper 3 wherein the pulley 30 is materially above the roll 11, the pulley 3| is materially below said roll, and the pulley 32 is sub stantialy midway between the axis of the pulley 3| and the axis of the roll y and rearwardly of said roll. It is also important to note that the axis of the roll 1/ is radially and rearwardly offset from a line extending from the axis of the pulley 30 to the axis of the pulley 3| in all of its positions as set by the cross-head 31.

The run of the belt 29 from the pulley 3| to the pulley 30 has a segmental wrap, at its intermediate portion, around the roll of paper 11 at the back thereof, or in other words, the roll 3,! holds the belt 26 rearwardly bowed between the pulleys 3| and 30. The end portions of this run of the belt 29 extend longitudinally from the roll y in diverging relation. The pulley 32 holds the two runs of the belt 29 that extend thereto and therefrom substantially at right angles to each other and out of contact wih the run of said belt having frictional contact with the roll 1/. The belt 29 is driven in the direction of the arrows marked thereon in Fig. 1, by the pulley 30 on the driven shaft 33, and said belt and the web 10 leave the roll y at substantially the same point and in diverging relation.

It may be here stated that the belt 29 is preferably driven at a speed, say two per cent (2%) less than that of the lineal travel of the web w Kit.

and thus places a drag on the rotation of the roll 11,

In addition to the spring-pressed roll 21 and the movable pulley 3|, the tension of the web w is further controlled by a floating governing roll 41 journaled on the free ends of a pair of arms 48 keyed to a rock shaft 49 journaled in bearings All 50 anchored to the floor l4. Fixed to the rock shaft 49 is a rod which projects therefrom in the opposite direction from the arm 48. Counterweights 52 are mounted on the rod 5| for adjustment toward or from the roll 41. The floating governing roll 41 extends transversely of the web w and rests thereon between the rolls 24 and 25 above the floor H.

The counterweights 52, as shown, are adjusted on the rod 5| for a full length roll of paper, but they may be adjusted for a three-quarter length roll or a one-half length roll. These counterweights 52 may also be adjusted relative to the governing roll 41 to cause said roll, which rests on the web w, to hold said web under a predetermined web tension and in balance.

To prevent the governing roll 41 from being lifted by the web w when given a udden pull, for instance, when a new roll of paper is swung into contact therewith by the reel l1, while being moved into active position, I provide a dashpot 53 containing a body of oil on which rests a plunger 54 loosely fitted in said dashpot. This plunger 54 is provided with a rod 55 which works through the top of the dashpot 53 and is loosely connected to the rod 5|. In the top of the dashpot 53 is an air relief port 56.

The piston 42 is operated by fluid under a predetermined pressure to move the pulley 3| downwardly in the cross-head guide 38, and take up the run of the belt 29 between the pulleys 38 and 3|, as the length thereof is progressively shortened by the diminishing diameter of the expiring roll y as its web w is unwound therefrom. This compressed fiuid hereinafter referred t s ai'rffo'ftl'igsakef'oflipnvenience, 1s conveye from marries tank 51 to the cylinders 4| above their pistons 42 through a main pipe line comprising sections 58 and 58', and branch pipes 59 leading from the pipe sections 58' to said cylinders. A hand valve 68 is interposed in each branch pipe 59. Air is supplied to the storage tank 51 by a compressor 6| actuated by an electric motor 62.

A valve casing 63 connects the pipe sections 58 and 58' and mounted in said casing is a reducing valve 64 that may be set, at will, to tend to maintain a constant pressure in outlet pipe 58' in accordance with the setting of valve 64 Also leading from the storage tank 51 is a pipe line comprising sections 65 and 65', the delivery end of the pipe section 65' being connected into the pipe section 58, which is on the discharge side of the valve casing 63.

Interposed in the pipe section 65, i Fig. 8) above the floor I4 and under one of the arms 48, is a valve casing 66 for an air-reducing valve and an air relief valve, and which casing comprises upper and lower sections between which a diaphragm 61 is clamped. This diaphragm 61 divides the valve casing 66 into an upper chamber 68 and a lower chamber 69. Formed in the valve casing 66 is a port 18 which extends radially into the lower chamber 69 and forms a continuation of the pipe section 65 which leads from the storage tank 51 to the intake side of the valve casing 66. The port 10, at its inner end. is normally closed by an automatic air-reducing ball valve 1|, and the pipe section 65 leading from the discharge side of the valve casing 66 is connected into the lower chamber 69.

A sleeve-like assembly 12 is secured to the diaphragm 61, and the opening therethrough affords a communicating port 13 between the two chambers 68 and 69. An automatic air relief ball valve 14 normally closes the port 13. Both valves H and 14 are mounted on a common carrier 15 in the lower chamber 69 and are arranged to close both ports 10 and 13 by an upward vertical movement thereof, and which ports are axially aligned with the valve casing 66 and with each other. A coiled spring 16, mounted in a seat therefor in a screw plug 11 closing an opening in the bottom of the valve casing 66, engages the lower end of the valve carrier 15 and yieldingly holds said carrier with the valves 1| and 14 positioned to close the respective ports 18 and 13. In the walls of the upper section of the valve casing 66 is a. plurality of air escape holes 18. Within the upper chamber 68 is a coiled spring 19 which rests on the diaphragm 61, and its lower end portion encircles the assembly 12 which affords a spring base therefor. On the upper end of the spring 19 is a spring cap 88 having at the axis of said spring a concave seat in which the rounded lower end of a push-rod 8| is seated. This push-rod BI is axially aligned with the valve casing 66 and extends through a bushing in the top of said casing with freedom for endwise sliding movement. The push-rod 8| at its upper end, is engaged by one of the arms 48 and may be depressed thereby to open the valve 14, as will presently appear.

A valve casing 82 (Fig. 1) connects the two pipe sections and 65' and is provided with a lower valve chamber 83, an upper valve chamber 84 and an axial passageway 85 connecting said two chambers. The pipe section 65 is connected into the lower valve chamber 83, and the pipe section 65' is connected into the passageway 85. Within the valve chamber 83 is an automatic valve 86 for opening and closing the air supply through the valve casing 82 from the pipe section 65 to the pipe section 65'. An automatic relief valve 81 in the valve chamber 84 is provided for opening and closing the passageway 85. These two valves 86 and 81 are carried on the rod 88 of a piston 89, which works in a cooperating cylinder 98 mounted on top of the valve casing 82. A relief port 9| in the valve casing 82 leads from the chamber 84 to asmosphere. This relief port 9| is simultaneously opened and closed with the passageway 85 by the relief valve 81. The valves 86 and 81 are arranged to be alternately opened and closed and a coiled spring 92, compressed between the bottom of the valve casing 82 and the valve 86, is under strain to close the valve 86, open the valve 81 and hold the piston 89 in its uppermost position.

Oil under pressure is provided for operating the piston 89 to open the valve 86 and close the valve 81 during the operation of the printing press. The system for supplying oil under pressure to the cylinder 98 includes a supply tank 93. a pipe 94 leading from the tank 93 to the cylinder 90, on the opposite side of the piston 89 from the valves 86 and 81, and a return pipe leading from said cylinder to the supply tank 93. Interposed in the pipe 94 is a pump 96 for circulating oil from the supply tank 93 through the pipe 94, cylinder 98 and pipe 95 to said tank. Connections 91 drive the pump 96 from a moving part of the printing press having a variable speed. A hand-operated cut-oil valve 98 is in- Bl i inder1 terposed in the pipe 95' to restrict its oil-conducting capacity and thereby cause the desired oil pressure to be built up in the cylinder 90 by the pump 96.

In place of operating the pulley 3| of each unit, by means of the air cylinder 4| and cooperating piston 42, the same may be operated by a weight 99 connected by a cable I to the yoke 44 on the cross-head 39. runs over a guide sheave I03 on the shaft 45, see Figs. and 11.

The weight 99, as shown in the drawings, is intended as an emergency means for operating the cross-head 31 in case the air supply to the cylinder 4| should fail. When the cross-head 31 is being operated by compressed air, the table |0I will be detached from the yoke 44 but in case the compressed air supply should fail, the cable |0I may be readily attached to the yoke 44 with very little delay in the operation of the printing press.

Referring now to the invention shown in Fig. 12, parts thereof that are like parts shown in Figs. 1 to 11, inclusive, are given the same reference numeral followed by a prime with the exception that the roll and its web are designated y y and y" respectively. In place of the endless friction belt 29, a friction strap I04 is used. One end of the strap I04 is anchored above the roll y, as indicated at I05, and the other end thereof is anchored below said roll, as indicated at I06. This strap I04 between the roll 11 and its anchored lower end passes around the pulley 3|. The pulley 3| and anchor I05 hold the section of the strap I04 in the same manner in which the belt 29 is held by the pulleys 30 and 3|. The section of the strap between the pulley 3| and the anchor I06 is held in the same position as the run of the belt 29 between the pulleys 3| and 32. As the function of the strap I04 is substantially the same as that of the belt 29, it is not thought necessary to describe the action thereof on the roll 11.

Operation It may be assumed that the printing press is stopped and as the web w is not being drawn into said press, the roll 3/ is idle. Also it may be assumed that the roll :1 is a full roll. The compressor 6| is intermittently and automatically operated by the motor 62 to maintain an air pressure in the supply tank 51 ofsay ninety .(90) pounds.

Compressed air from the storage tank 51 is constantly supplied to the cylinder 4| through the pipe sections 58 and 58' and branch pipes 59, and holds the pistons under a minimum pressure of say fii'teen pounds. The reducing valve 64 in valve casing 63 is set to maintain this minimum air pressure in the cylinders 4| and enough more to compensate for leakage through the air vent 9| in the valve casing 82 to atmosphere. As the printing press is not running the fluid pump 96 is idle and hence the spring 92 is yieldingly holding the valve 86 closed and the relief valve 81 open.

The governing roll 41 is balanced by the weights 52 to hold the air-reducing valve 1| open to permit air pressure of say thirmfiilli pounds through the valve casing 66, which may be assumed to be the desired air pressure to be maintained in the cylinders 4| when the printing press is running at normal or printing speed. However, the air supply from the storage tank 51 to the cylinders 4| through the pipe sections 65, 65 and 58', branch pipes 59 and valve casings 66 and 62, is closed by the valve 86 when the printing press is stopped.

This cable I00 I At the time the printing press is stopped, the spring-actuated roll 23 is moved by the springs 20 from its dotted line position to its full line position, see Fig. 1, and takes up any slack placed in the web w by movement of the roll y under its momentum.

From the above description, it is evident that the roll 11, when the printing press is stopped, is held under braking action produced by the friction belts 29 on said roll, and said belts are held under tension by the pulleys 3| which are subject to the fifteen (15) pounds of air pressure on the pistons 42.

Upon starting the printing press, the pull thereof on the web w will first straighten the run of said web between the directional rolls 24 and 25 and thereby lift the governing roll 41. This lifting of the governing roll 41 will relieve its pressure on the plunger BI and permit the valve 1| to close or partially close, but this has no effect on the air pressure in the cylinder 4|, for the reason that when the valve 86 is closed, the pump 96 has not been operated for a sufficient length of time to build up an air pressure in the cylinder to operate the piston 89 and open the valve 86. The dashpot 53-54 will prevent sudden lifting of the governing roll 41.

Following the lifting of the governing roll 47, the press pull on the web w will retract the roll 23 until its actuating springs 28 are compressed approximately fifty per cent (50%). Obviously, the action of the governing roll 41 and the springactuated roll 23 on the web 10, during the initial starting of the printing press, will cause the web w, under the pulling action thereon by said press, to gradually overcome the inertia of the roll y and start the turning thereof without a sudden pull thereon that would cause the roll y to run ahead and put slack in said web. Slack in the web 10 produces an uneven tension thereon and a possible breaking of the web w when the slack is taken up by the pull of the printing press.

As the speed of the printing press increases, the pump 96 operates thereby, builds up suflicient air pressure in the cylinder 88 to move the piston 89 and thereby close the valve 81 and gradually open the valve 86. The closing of the valve 81 closes the air escape vent 9| and the opening of the valve 06 gradually increases the air pressure from the storage tank 51 to the cylinder 4| until the air pressure on the pistons 42 has reached the normal maximum air pressure of thirty (30) pounds. It may be here stated that the governing roll 41, immediately after the lifting thereof by the straightening of the respective run of the web w, will be returned by gravity to normal position, and thereby resets the valve 1| for air pressure of thirty (30) pounds. During the gradual increase of air pressure in the cylinders 4|, the tension on the belts 29 is likewise increased thereby, and this increased tension on the belts 29 progressively increases the friction on the roll y and hence a greater braking action on the roll 11, as the lineal travel of the web w from the roll y to the printing press increases.

As the diameter of the roll y is progressively decreased by the unwinding of the web w therefrom, the length of the run of the belt 29 between the pulleys 30 and 3| is progressively shortened and this shortening of the respective run of the belts 29 is taken up, as the same develops, by the pulleys 3| which are progressively moved away from the pulleys 32 by air pressure in the cylinders 4| acting on the pistons 42.

It was heretofore stated that a progressively decreasing effort was required to control the roll 11 as the diameter thereof progressively decreased, and this decreasing diameter of the roll 11 progressively decreased the length of the circumferential wrap of the belts 29 on the periphery of the roll y. As the decreasing length of the wrap of the belts 29 on the roll y is somewhat greater than the effort desired to control the roll y in its highest efiiciency, the length of this wrap is progressively decreased as the diameter of the roll 3,! decreases, by moving the pulleys 3| farther away from the pulleys 32. In other words, the pulleys 3| are moved farther under the roll and away from the side of said roll from which the web w is leaving the same as the diameter of the roll decreases.

The novel arrangement of the pulleys 30, 3|

and 32, relative to the roll 11, is highly important and particularly where one of the two pulleys, that holding the end portions of the respective run of the belt 29 tangentially to the roll on opposite sides thereof, and with the intermediate portion of said run wrapped circumierentially on the periphery of said roll, is automatically moved bodily outwardly with the respective tangential end portion of the web as the same progressively lengthens under the action of the progressively diminishing diameter of the roll y, as its web w is unwound therefrom. This bodily movable pulley not only progressively decreases the length of the circumferential wrap of the belt with the roll, as the diameter of said roll progressively decreases, but due to its close proximity to the roll y, is very sensitive to any tension variation in the run of the belt 29 contacting the roll 11, due to an unevenly wound roll or other causes, and automatically compensates therefor and keeps the respective run of the belt 29 under a constant and even tension.

As the belts 29 are spaced edgewise apart axially of the roll y and substantially equal distances apart, and as each thereof is independently and automatically controlled, the frictional contact between the roll 31 and belts 29 is the same at all contacting points so that the roll 11 is evenly controlled throughout its entire length.

In case the printing press is suddenly stopped, the momentum of the roll 1,! will put slack in the web w and cause the governing roll 41 to drop by gravity which, together with the retracted spring-pressed roll 23, will take up this slack. This dropping of the governing roll 41 will force the plunger 8| downwardly and thereby further open the valve 1| and allow an increased air pressure to flow from the storage tank 51 to the cylinders 4|. This increased air pressure in the cylinders 4| will press the pistons 42 further downwardly in said cylinders and thereby increase the tension on the belts 29 and hence the friction or braking effort on the roll 11, and thereby prevent further turning thereof under momentum.

At the time the active roll y is expiring, the pistons 42 are at their lowermost positions in the cylinders 4| and the run of the belts 29 between the pulleys 3D and 3| is at its shortest length. As the roll 11 is expiring, the reel I1 is operated to move the new full roll 2 into the place of the expired roll y. Swinging the roll 2 from its idle position to its active position will cause the same to engage the runs of the belts 29 between the pulleys 39 and 3| and thereby draw the belts over the pulley 3| and away from the pulleys 32.

This movement of the belts 29 increases the length of its runs between the pulleys 30 and 3| to their maximum length and also moves the Examiner cross-heads 31 and the pulleys 3| mounted therein upwardly in the cross-head guides 38. Movement of the cross-heads 31 upwardly in the cross-head guides 38 moves the pistons 42 upwardly in the cylinders 4| and thereby produces back pressure and forces the air in said cylinder through the branch pipes 59, pipe sections 58 and 65', valve chamber 93, pipe section 65' and into the valve chamber 69, where the same lifts the diaphragm 61, opens the valve 14 and allows the air to escape through the port 13 to the chamber 68 and from thence through the holes 18 to atmosphere. As the diaphragm 61 is 1 e y back air pressure, the spring 16, acting on the valve carrier 15, closes the valve 1|. As soon as air pressure in the chamber 69 is reduced to normal, the diaphragm 61, acted on by the spring 19, closes the valve 14 and opens the valve 1|.

In place of the cylinders 4| and the co-operating pistons 42, the cross-heads 31 may be operated by means of the weight 99. In case air pressure to the cylinders 4| should fail, the change from air pressure to the weight 99 only necessitates the attachment of the cable N10 to the yokes 44.

It is, of course, understood that the anchored straps shown in Fig. 12 may be used in place of the belts 29 or a combination of said straps and belts used.

The automatically controlled variable braking effort I use in connection with the roll of paper, as its web is being drawn into a printing press and the tension on said web is highly important during acceleration, normal running speed and deceleration of a printing press or the sudden stopping thereof. This invention is especially eflicient during the preparation of a printing press for running when it is necessary to make many starts and stops of said press during plating thereof. During this plating-up process, the pull of the press on the web of paper is uneven due to the plates being unevenly distributed on the cylinders. If the tension on the web of paper were as great during the time the press is being plated as it is when the press is running, then said web would break due to the uneven pull thereon, thus causing waste and delay.

By manipulating the hand valves 60, the air pressure in the cylinders 4| may be manually controlled; at will.

The drawings illustrate a commercial form of the invention, but it will be understood that the same is capable of a large range of modifications within the spirit of the invention herein disclosed and broadly claimed.

What I claim is:

1. Mechanisn for controlling a roll of web material and tensioning its unwound web between said roll and a printing press or other machine into which said web is fed, comprising a friction strap-like member, a pair of devices for holding said member, means for supportin a roll of web material between said devices, a bodily movable direction-changing device engaging said member, forming a loop therein between one of the devices of said pair and the roll and holding a section of said member bowed and wrapped circumferentially around the periphery of the roll, and means operable on the direction-changing device for holding said member under tension and for moving the direction-changing device in a direction to decrease the circumferential wrap of said member on the roll as the diameter of said roll is decreased by unwinding its web therefrom, the operating means for the direction-changing device holding said friction member under a predetermined minimum tension when the machine is stopped, and including mechanism, controlled by a part of the machine that moves at a variable speed, for progressively increasing the tension on said member during acceleration of the machine, holding said member at a predetermined tension during normal running of the machine and progressively decreasing said tension during deceleration of the machine.

2. Mechanism for controlling a roll of web material and tensioning its unwound web between said roll and a printing press or other machine into which said web is fed, comprising a friction strap-like member, a pair of devices for holding said member, means for supporting a roll of web material between said devices, a bodily movable direction-changing device engaging said member, forming a loop therein between one of the devices of said pair and the roll and holding a section of said member bowed and wrapped circumferentially around the periphery of the roll, and means operable on the direction-changing device for holding said member under tension and for moving the direction-changing device in a direction to decrease the circumferential wrap of said member on the roll as the diameter of said roll is decreased by unwinding its web therefrom, the operating means for the direction-changing device holding said friction member under a predetermined minimum tension when the machine is stopped, and including mechanism, controlled by a part of the machine that moves at a variable speed, for progressively increasing the tension on said member during acceleration of the machine, holding said member at a predetermined tension during normal running of the machine and progressively decreasing said tension during deceleration of the machine, said operating means further including other mechanism, controlled by the tension of the web, for increasing the tension on said member during normal running of the machine in case tension on the web drops below a predetermined tension.

3. Mechanism for controlling a roll of web material and tensioning its unwound web between said roll and a printing press or other machine into which said web is fed, comprising a friction strap-like member, a pair of devices for holding said member, means for supporting a roll of web material between said devices, a direction-changing pulley engaging said member, forming a loop therein between-one of the devices of said pair and the roll and holding a section of said member bowed and wrapped circumferentially around the periphery of the roll, a cross-head on which the pulley is journaled, a guide for the crosshead, and means operative on the cross-head for holding said member under tension, said guide being arranged to direct the pulley to progressively decrease the circumferential wrap of said member on the roll as the diameter or said roll is progressively decreased by unwinding its web therefrom.

4. Mechanism for controlling a roll of web material and tensioning its unwound web between said roll and a printing press or other machine into which said web is fed, comprising a friction strap-like member, a pair of devices for holding said member, means for supporting a roll of web material between said devices, a bodily movable direction-changing device engaging said member, forming a loop therein between one Of the devices of said pair and the roll and holding a section of said member bowed and wrapped circumferentially around the periphery of the roll, a co-operating cylinder and piston for moving the direction-changing device in a direction to progressively decrease the circumferential wrap of said member on the roll as the diameter of the roll is progressively decreased by the unwinding of its web therefrom, a source of fluid under pressure, and means for supplying fluid from said source to the cylinder.

5. The structure defined in claim 4 in which the means for supplying fluid to the cylinder further includes a reducing valve.

6. The structure defined in claim 4 in which the means for supplying fluid to the cylinder further includes a reducing valve, and means controlled by the tension of the web for holding the reducing valve in a predetermined open position.

7. The structure defined in claim 4 in which the means for supplying fluid to the cylinder further includes a reducing valve, and means controlled by the tension of the web for holding the reducing valve in a predetermined open position and for opening the reducing valve to a greater fluid-conducting capacity when the tension on the web is reduced below a predetermined tension.

8. The structure defined in claim 4 in which the means for supplying fluid to the cylinder further includes a reducing valve and a relief valve.

9. Mechanism for controlling a roll of web material and tensioning its unwound web between said roll and a printing press or other machine into which said web is fed, comprising a friction strap-like member, a pair of devices for holding said member, means for supporting a roll of web material between said devices, a bodily movable direction-changing device engaging said member, forming a loop therein between one of the devices of said pair and the roll and holding a section of said member bowed and wrapped circumferentlally around the periphery of the roll, a co-operating cylinder and piston for moving the direction-changing device in a direction to lengthen said loop and thereby progressively decrease the circumferential wrap of said member on the roll as the diameter of the roll is progressively decreased by the unwinding of its web therefrom, a source of fluid under pressure, means for supplying fiuid from said source to the cylinder, at a relatively low pressure, and further means controlled by a part of said machine that moves at a variable speed for supplying fluid from said source to the cylinder at a pressure that progressively increases from said low pressure up to a maximum pressure during normal running of the machine, and that progressively decreases to said low pressure during deceleration of said machine.

10. The structure defined in claim 9 in which the means for supplying fiuid from said source further includes a reducing valve, and means controlled by the tension of the web for holding said valve open at substantially said maximum pressure and for opening said valve to a greater fluidconducting capacity when the tension on the web is reduced below a predetermined tension.

HERBERT A. LOTZ. 

